Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python2.7/py_compile.py", line 117, in compile
    raise py_exc
py_compile.PyCompileError:   File "/in/foo.py", line 9
    price = float(input(f"请输入购买的第{i}种图书价格（元）："))
                                                                             ^
SyntaxError: invalid syntax